Nigeria’s currency slumped to an all-time low against the U.S. dollar Wednesday, pummeled by the tumbling price of oil, rendering the central bank’s staunch efforts to stem the decline ineffective.

The dollar rose as high as 187 naira in early afternoon, eclipsing a previous record of 186.90 set on Dec. 2. That brings the buck’s year-to-date climb against the naira to 16.8% and its appreciation so far in December to 4.7%.